Process of producing low-carbon ferro-alloys.



ame time ora ion. I

ISAAC R. EDMANDS, OF NIAGARA FALLS, NEW YORK, ASSIGNOR' TO ELECTROMETAL- LURGIGAL COMPANY, OF CHICAGO, ILLINOIS, A. CORPORATION OF WESTVIRGINIA.

PROCESS OF PRODUCING LOW-CARBON FERRO-ALLOYS.

No Drawing.

To all whom it may concern:

Be it known that I, IsAAo R. EDMANDS, a

citizen of the United States, residing at- Niagara Falls, in the countyof Niagara and .bon ferro-alloys comprises two stages. In

the first stage, a high-carbon ferro-alloy, for example one of chromium,molybdenum, tungsten, titanlum, vanadlum or nickel, 1s

cheaply produced by smelting a mixture of an ore of the alloying metal,an excess of carbon and a source of iron. The reduction may be effectedin an ordinary electric furnace having a carbon lining and dependingcarbon electrodes. In the second stage, the carbon is removed or reducedto a small percentage by heating the molten alloy to a temperature suchthat the afiinity of oxygen for the contained carbon is greater than itsafiinity for the chromium or other alloyed metal, and then subjecting itfor a limited period to the action of air or other oxidizing gas. In theordinary Bessemer process of producing steel, the molten pig-ironcontaining a small amount of silicon or other highly-positive metal andcarbon 1S subjected to the action of airv at temperatures such that theafiinity of oxygen for the silicon or other alloyed positive metal isgreater than its affinity for carbon, so that the removal of the alloyedmetal substantially precedes the removal of carbon. But

when the temperature of one of the specified alloys of iron, ahighly-positive metal and carbon, is raised to a temperature above that.employed in the Bessemer steel lndustry or usually produced bycombustion but readilyobtainable in an electric furnace, for example atemperature betweei1-1600 C. and

' 2500 C. the relative afiinities of the alloyed metal and carbon towardoxygen change, the

, heat of combination of the carbon and oxygen becomes greater than theheat of com- Speeification of Letters Patent.

bination of the alloyed metal and oxygen, and the carbon may then belargely or substantially eliminated by oxidation before any considerablepercentage of the alloyed metal 1s removed.

In carrying out the second stage of the process, the ferro-alloy high incarbon may be subjected to the action of the oxidizinggas in theelectric furnace in which it has been produced, as by providing thelower end of the furnace with openings and forcing air through theseopenings and through the molten alloy. Or the alloy may be tapped from.the electric reduction furnace, at a high temperature, into a separatevessel, and therein treated with the oxidizing as, more heat beingsupplied if necessary, eit er by an arc, or by passing an electriccurrent through the alloy, acting as a resistor, or through a slag orother resistor in contact with or proximity to the alloy. Or the castPatented June 3, 1913. Application filed September M, 1907. Serial No.394,272. 1

alloy may be remelted and electrically heated to the requisitetemperature. The air or other oxidizing gas may either be forced throughthe alloy or caused to act upon its surface, as in the present art ofbessemerizmg pig-iron.

The term ferro-alloys, as used in the claims, means a product in whichthe metal alloyed with iron is the important and valuable constitutent,as distinguished from pigiron, which may contain one or two per cent. ofsilicon and manganese.

I claim:

1. The process of producing low-carbon ferro-alloys, which consists infirst producing a ferro-alloy high in carbon, and then subjecting theproduct, heated to a temperature such that the aflinity of oxygen forthe contained carbon is greater than its affinity for the alloyed metal,to the action of an oxidizing gas.

2. The process of producing low-carbon ferro-alloys, which consists infirst producing a ferro-alloy high in carbon, and then subjecting theproduct, electrically heated to a temperature such that the affinity ofoxygen for the contained carbon is greater than its afiinity for thealloyed metal, to the action of an oxidizing gas.

3. The process of producing low-carbon ferroalloys, which consists inelectrically smelting acompound of the alloying metal, an excess ofcarbon and a source .of iron,

and subjecting the high-carbon product, elec- 11c trically heated to atemperature such that the aflinity ofoxygen for the contained carbon isgreater than its afiinity for the alloyed metal, to the action of anoxidizing as.

b 4. The process of producing low-carbon ferrochromium, which consistsin first producing ferrochromium high in carbon, and

then subjecting the product, heated to a temperature such that theatfinity of oxygen for the contained carbon is greater than its aflinityfor the chromium, to the action of an oxidizing gas.

' 5. The process of producing low-carbon ferrochromium, which consistsin first producing ferrochromium high in carbon, and then subjecting theproduct, electrically heated to a temperature such that the afiinity ofoxygen for the contained carbon is greater than its aflinity forchromium, to the action of an oxidizing gas.

6. The process of producing low-carbon ferrochromium, which,consists inelectrically smelting a compoun of chromium, an excess of carbon and asource of iron, and subjecting the high-carbon product, electricallyheated to a temperature such that'the afiinity of oxygen for thecontained carbon is greater than its affinity for chromium, to theaction of an oxidizing gas.

7. The process of producing low-carbon ferro-alloys, which consists infirst producing a ferro-alloy high in carbon, and then subjecting theproduct, heated to a temperature above 1600" 0., to the action of anoxidizing gas.

In testimony whereof, I afiix my signature in presence of two witnesses.

ISAAC R. EDMANDS. WVitnesses:

E. F. PRICE, G. E. Cox.

